The present invention relates to a hose belt conveyor system having a conveyor belt that is made of rubber or rubber-like synthetic material, contains filamentary load-carriers which extend in the longitudinal direction of the belt, and that can be closed, by overlapping its longitudinal edge regions, to form a hose belt that is supported all the way around by support rollers, with these rollers being divided into garlands of rollers; in particular, in a given stretch of the conveyor system that has been closed in the manner of a hose, a first garland of rollers is provided that substantially surrounds the lower half of the cross section of the hose belt, and a second garland of rollers is provided that substantially surrounds the upper half of the cross section of the hose belt.
Systems of this general type are described in Canadian patent application Ser. No. 516,229-Engst, filed Aug. 19, 1986, and in U.S. patent application Ser. No. 833,903, filed Feb. 26, 1986, now U.S. Pat. No. 4,723,653-Engst dated Feb. 9, 1988 both of which belong to the assignee of the present application.
Hose belt conveyor systems are described, for example, in German Patent 943 817 Gielen dated June 1, 1956, German Offenlegungsschrift 1 934 342 Bouzat et al dated July 16, 1970, and German Patent 2 944 448 Hashimoto et al dated May 21, 1981. The drawback with the known systems of this type is that the support and guide rollers, which support the conveyor belt and guide it in hose form, are rigidly disposed around the cross section of the belt, and have a constant symmetrical distribution therearound. As a result of this rigid arrangement of the rollers, a specific hose cross section, which is prescribed exactly by the position of the rollers, is constantly forced upon the conveyor belt, and this is true independent of the shape and distribution of the material that is being transported at any given time. With such a configuration, the material of the belt is greatly stressed, especially when bulky material is conveyed, which could damage the belt. The heretofore known hose belt conveyor systems also have the drawback that the assembly of the conveyor belt, as well as maintenance and repair, is very expensive, since the conveyor belt is very inaccessible due to the support frame that surrounds it, and on which the rollers are fixedly mounted.
To avoid these drawbacks, it was proposed in applicant's above mentioned applications, to divide the support rollers of a hose belt conveyor system into garlands of rollers. In particular, in a given stretch of the conveyor system that has been closed in the manner of a hose, a first garland of rollers was provided that essentially surrounds the upper half of the cross section of the hose belt, and a second garland of rollers was provided that essentially surrounds the lower half of the cross section of the hose belt. Preferably, a lower roller garland is associated with each of the upper roller garlands, with the upper and lower roller garlands being disposed either exactly across from one another, or being offset slightly relative to one another, when viewed in the longitudinal direction of the belt.
Pursuant to one advantageous embodiment, the aforementioned system took into account the fact that with the previously known hose belt conveying systems, due to their rigid arrangement of the support rollers, the longitudinal edge of that belt edge region which overlaps during formation of the hose frequently collides with the end face of the adjacent lateral support roller. Over time, this can result in damage to this longitudinal edge of the belt, which necessitates expensive repair or even replacement of the entire belt.
To resolve this problem, it was proposed that in the upper roller garlands, the distance between those two rollers that are disposed on both sides of the longitudinal edge of the overlapping belt edge region be greater than the distances between the remaining rollers. This prevents these longitudinal belt edges from striking the end faces of the laterally adjacent roller, and thus becoming damaged, when slight fluctuations or twists of the moving hose belt are encountered. This increased roller gap was realized in particular by placing between the two aforementioned rollers that are disposed on both sides of the longitudinal edge of the belt, a connecting link that is longer than the other connecting links of the remaining rollers of the upper garlands, with the rollers themselves all having the same dimensions.
However, experience has, in the meantime, shown that these measures are not always suitable or satisfactory to prevent the edge of the belt from contacting the end face of the adjacent lateral support roller under all operating conditions that occur in practice, especially where the system passes through a narrow curve, or where the load on the belt fluctuates greatly.
It is therefore an object of the present invention to provide an improved hose belt conveyor system where contact of the belt edge against the end face of the adjacent lateral support roller is reliably avoided under all operating conditions.